Gear

56 ''' Class that represents the combination of two motors on an axis 57 to perform a car-like movement. 58 '''

59 - def __init__(self, port1 = MotorPort.A, port2 = MotorPort.B):

60 ''' 61 Creates a gear instance with left motor plugged into port1, right motor plugged into port2 62 (defaults: port1 = MotorPort.A, port2 = MotorPort.B). 63 ''' 64 self.mot1 = Motor(port1) 65 self.mot2 = Motor(port2) 66 self.gearState = GearState.STOPPED 67 self.speed = SharedConstants.GEAR_DEFAULT_SPEED 68 self.mot1.setSpeed(self.speed) 69 self.mot2.setSpeed(self.speed) 70 self._bt = None # BreakThread 71 self._arcRadius = 0

72

73 - def setSpeed(self, speed):

74 ''' 75 Sets the speed to the given value (arbitrary units). 76 The speed will be changed to the new value at the next movement call only. 77 @param speed: the speed 0..100 78 ''' 79 self.speed = speed 80 self.mot1.setSpeed(speed) 81 self.mot2.setSpeed(speed) 82 self.gearState = GearState.UNDEFINED

83

84 - def getSpeed(self):

85 ''' 86 Returns the current speed (arbitrary units). 87 ''' 88 return self.speed

89

90 - def forward(self, duration = -1):

91 ''' 92 Starts the forward movement with current speed for the given duration (in ms). 93 For duration = -1 (default), the method returns, while the movement continues. 94 Otherwise the method returns at the end of the given duration, but the 95 movement continues for 200 ms. Then it stops unless another movement method 96 call (forward, backward, left, right, leftArc, rightArc) is 97 invoked within that time. In a consequence calling several movement methods 98 one after the other will result a seamless movement without intermediate stops. 99 (If motor is already rotating with same speed, returns immediately.) 100 ''' 101 Tools.debug("calling forward() with speed: " + str(self.speed) + " and duration: " + str(duration)) 102 self._joinBrakeThread() 103 if duration == 0 or (duration < 0 and self.gearState == GearState.FORWARD): 104 return 105 self.mot1.forward() 106 self.mot2.forward() 107 self.gearState = GearState.FORWARD 108 if duration > 0: 109 Tools.delay(duration) 110 self._startBrakeThread()

111

112 - def backward(self, duration = -1):

113 ''' 114 Same as forward(int duration), but moves in reverse direction. 115 ''' 116 Tools.debug("calling backward() with speed: " + str(self.speed) + " and duration: " + str(duration)) 117 self._joinBrakeThread() 118 if duration == 0 or (duration < 0 and self.gearState == GearState.BACKWARD): 119 return 120 self.mot1.backward() 121 self.mot2.backward() 122 self.gearState = GearState.BACKWARD 123 if duration > 0: 124 Tools.delay(duration) 125 self._startBrakeThread()

126

127 - def stop(self):

128 ''' 129 Stops the gear. 130 (If motor is already stopped, returns immediately.) 131 ''' 132 Tools.debug("calling stop()") 133 self._joinBrakeThread() 134 if self.gearState == GearState.STOPPED: 135 return 136 self.mot1.stop() 137 self.mot2.stop() 138 self.gearState = GearState.STOPPED

139

140 - def moveTo(self, count, blocking = True):

141 ''' 142 Sets the rotation counter of both motors to zero and rotate the motors until the given count is reached. 143 If count is negative, the motors turn backwards. 144 If blocking = True (default), the method returns blocks, until the count is reached; otherwise it returns 145 immediately 146 ''' 147 self.mot1.rotateTo(count, False) 148 self.mot2.rotateTo(count, blocking)

149

150 - def left(self, duration = -1):

151 ''' 152 Starts turning left with left motor rotating forward and 153 right motor rotating backward at current speed. 154 For duration = -1 (default), the method returns, while the movement continues. 155 Otherwise the method returns at the end of the given duration, but the 156 movement continues for 200 ms. Then it stops unless another movement method 157 call (forward, backward, left, right, leftArc, rightArc) is 158 invoked within that time. In a consequence calling several movement methods 159 one after the other will result a seamless movement without intermediate stops. 160 (If gear is already turning left, returns immediately.) 161 ''' 162 self._joinBrakeThread() 163 if duration == 0 or (duration < 0 and self.gearState == GearState.LEFT): 164 return 165 self.mot1.backward() 166 self.mot2.forward() 167 self.gearState = GearState.LEFT 168 if duration > 0: 169 Tools.delay(duration) 170 self._startBrakeThread()

171

172 - def right(self, duration = -1):

173 ''' 174 Same as left, but turns to the right. 175 ''' 176 self._joinBrakeThread() 177 if duration == 0 or (duration < 0 and self.gearState == GearState.RIGHT): 178 return 179 self.mot1.forward() 180 self.mot2.backward() 181 self.gearState = GearState.RIGHT 182 if duration > 0: 183 Tools.delay(duration) 184 self._startBrakeThread()

185

186 - def leftArc(self, radius, duration = -1):

187 ''' 188 Starts turning to the left on an arc with given radius (in arbitrary units). 189 If the radius is negative, turns left backwards. 190 For duration = -1 (default), the method returns, while the movement continues. 191 Otherwise the method returns at the end of the given duration, but the 192 movement continues for 200 ms. Then it stops unless another movement method 193 call (forward, backward, left, right, leftArc, rightArc) is 194 invoked within that time. In a consequence calling several movement methods 195 one after the other will result a seamless movement without intermediate stops. 196 (If gear is already turning on a left arc with same radius, returns immediately.) 197 ''' 198 Tools.debug("calling leftArc() with radius: " + str(radius) + " and duration: " + str(duration)) 199 self._joinBrakeThread() 200 if duration == 0 or (duration < 0 and self.gearState == GearState.LEFTARC and self._arcRadius == radius): 201 return 202 speed1 = int(self.speed * (abs(radius) - SharedConstants.GEAR_AXE_LENGTH) / (abs(radius) + SharedConstants.GEAR_AXE_LENGTH)) 203 self.mot1.setSpeed(speed1) # Reduce speed of mot1 204 Tools.debug("speed1: " + str(speed1)) 205 Tools.debug("speed2: " + str(self.speed)) 206 if radius > 0: 207 self.mot1.forward() 208 self.mot2.forward() 209 else: 210 self.mot1.backward() 211 self.mot2.backward() 212 self.mot1.setSpeed(self.speed) # Restore old speed 213 gearState = GearState.LEFTARC 214 self._arcRadius = radius 215 if duration > 0: 216 Tools.delay(duration) 217 self._startBrakeThread()

Source Code for Module Gear